1. Field of the Invention
The present invention relates generally to magnetic sensing devices, and more specifically, to electronic circuitry for outputting a digital signal as a dynamic representation of an analog signal that is indicative of any rotational movement, any linear movement, and/or any angular movement of an object as sensed by a magnetic sensor.
2. Background
Magnetic sensors known in the art are operable to output an analog signal as a function of the magnetic flux density of any magnetic flux passing through one or more magnetic flux sensitive transducers of the magnetic sensor, e.g. a magneto-resistor, a Hall effect element, a coil, etc. The magnetic sensor is spatially positioned from an object to define an air gap area therebetween. A portion of a magnetic field traverses the air gap area, and the magnetic flux sensitive transducer(s) is (are) disposed within the magnetic field. As a result, the magnitude of the analog signal varies in response to any rotational movement, any linear movement, and/or any angular movement of the object that increases or decreases the reluctance across the air gap area to thereby alter the magnetic flux density of the magnetic flux passing through the magnetic flux sensitive transducer(s). Consequently, whenever any movement of the object undulates any magnetic flux passing through the magnetic flux sensitive transducer(s), a cycle or cycles of the analog signal is indicative of a degree of movement of the object, and a frequency of each cycle of the analog signal is indicative of a rate of movement of the object. Accordingly, the analog signal of a magnetic sensor has been and will continue to be extensively utilized by various electromechanical systems to ascertain the degree and the rate of any movement of an object. For example, magnetic sensors have been extensively incorporated in engine timing systems of motor vehicles to ascertain a number of rotations of a gear component and/or to ascertain a rotational speed of a gear component.
The utilization of the analog signal of a magnetic sensor as an input signal for a digital device of an electromechanical system requires the analog signal to be outputted as a square wave having a peak-to-peak amplitude consistently equating a logic low signal level and a logic high signal level of a square wave. However, it is essentially impossible to output the analog signal as a square wave. In addition, it is improbable for a magnetic sensor to output an analog signal having a consistent peak-to-peak amplitude, because the peak-to-peak amplitude of the analog signal is a function of various factors including, but not limited to, any changes in environmental conditions ambient to the magnetic sensor such as temperature, any changes in the magnetic induction of the magnetic field, any manufacturing imperfections or irregularities of the object, and any variance in the original geometric configuration and physical dimensions of the object. Thus, various digital circuits have been made to output a digital signal as a representation of each occurrence and frequency of every cycle of the analog signal. A problem associated with outputting the digital signal as such a representation is the aforementioned inconsistency of the peak-to-peak amplitude of the analog signal. One design approach to overcome this problem is the incorporation of an automatic gain control of the analog signal in combination with a static switching threshold for the digital signal. While this particular design approach of digital circuits limits the effects of the inconsistency of the peak-to-peak amplitude of the analog signal on the accuracy of the digital signal over a relatively long time period, this design approach does not dynamically address the effects of the inconsistency of the peak-to-peak amplitude of the analog signal on the accuracy of the digital signal.